We were snowshoeing the other day with folks who did not seem
to be Prepared for an adventure even a couple of miles back into the snowbound
wilderness.They each used a small "fanny pack". I asked them what they would do
to keep warm during an emergency stop and stranding - to care for an injured companion, or if the weather closed down to hard wind driven
rain or snow and familiar trails and ways disappeared.

All of them said they carried a "space
blanket" to keep them warm. There-in lies the
danger! Emergency space blankets provide a false sense of security!

I have heard this claim before, that "a space blanket provides warmth". I have
always understood that the
term "space blanket" is a misnomer: the thin plastic sheet is neither a miracle
material nor a blanket! "Blankets", thick or thin, trap air for insulation.
The
thicker the blanket the higher the insulation rating. (Blankets do not add heat unless
the blanket is warmed, as in an Emergency Room. Warmth must be added, under the
insulation).

It is well known that body heat is lost
in 5 specific ways: Convection, Conduction, Radiation, Evaporation and
Respiration. Excessive body heat loss leads quickly to hypothermia.

The thin shiny plastic sheet (heavily advertized as an
"Emergency Space Blanket") has no insulating qualities, indeed, the plastic immediately becomes
as cold as the rain or snow or the wind blown air and will immediately conduct that cold
through wet clothing to the human body. Also, it is almost impossible to
close out the cold wind. I learned this personally, at the
finish line of the New York Marathon in 1979.

If you lie
down on a plastic space blanket placed on the snow, the cold will immediately be
conducted directly to your compressed clothing. If your clothing is damp or
worse - wet to the skin, you might as well lie down in an ice cold mountain
stream.

An inexpensive alternative to the metalized Space Blanket, is
a common heavy duty trash bag (or two).

Convection
When wind blows against the skin or wet clothing, it helps speed up the
processes of evaporation, making the person become much colder (often described
as the wind chill factor). Technical under-layers that "keep the skin dry" help
block this factor. A mandatory waterproof-breathable (Gore-Tex) outer layer
breaths perspiration and keeps your insulating layers dry.

Conduction
Heat will be lost through contact with wet surfaces at a lower temperature than
that of the body. Technical under-layers that "keep the skin dry" help block
this factor. A mandatory waterproof-breathable (Gore-Tex) outer layer breaths
perspiration and keeps your insulating layers dry. You must carry a lite 6 oz.
insulating pad to shelter on snow or wet ground.

Radiation
Heat is lost through radiation from all over the body. This is the least
significant factor. Your clothing, hats and gloves help block radiation.

Evaporation
Heat is lost through the body's natural cooling system (perspiration) which
evaporates from the skin and clothing wet with sweat, melted snow, rain, stream
crossings and more. Technical under-layers that "keep the skin dry" help block
this factor. A Gore-Tex waterproof-breathable outer layer breaths perspiration
and keeps your insulating layers dry

RespirationThe only other way in which heat is lost is through respiration (breathing),
and this should be attended by covering the mouth and nose area with a wool
scarf or a special mask. You may need to stop, stay in one sheltered place and
limit your heat loss from heavy breathing while trying to find your way.

The English manufacturer of the Kelvalite 'Life Emergency Blanket'
describes how to use their product:

IMPORTANT
"It should be stressed here that the 'Life' Emergency Blanket should be used in
conjunction with any other hypothermia/core warming treatments if available -
however, in an emergency situation the 'Life' Blanket is far more efficient than traditional
cloth or synthetic blankets.

Using the 'Life' Emergency Blanket couldn't be easier - just unfold and wrap
around the patient.

To be at its most effective however, the points below should be observed:

Unfold the blanket completely and lay flat on the ground, preferably on as warm,
dry and insulated a surface as possible.

Lay the patient on the blanket, leaving about 12 inches of blanket overlapping
at the 'feet' end. The blanket is most effective when used directly next to the
skin - if required
material blankets may be wrapped on the outside of the Emergency Blanket.

Fold the end of the blanket over the feet, and bring the two sides up and over
to overlap at the top.

If possible secure the blanket with some tape - the better the seal the more
efficient the blanket will be.

Do not wrap too tightly as the air which is trapped contributes to the
insulation - see Technical Information section for further details.

Be sure that the feet, hands and as much of the head as possible are covered. If
necessary use another blanket (or a child size one) to wrap around the top of
the head,
leaving the nose and mouth uncovered.

Use an inhalation re-warming unit if available, or cover the mouth and nose with
wool or a handkerchief to help slow down heat loss through respiration.

The patient may complain of feeling clammy or uncomfortable - this is perfectly
normal and simply means that the blanket is working. The closed 'tube' means
that moisture cannot escape - this causes the humidity levels next to the skin
to increase, and slows down the patient's natural cooling system (evaporation via perspiration)."

The Thermo-lite "Emergency Bivvy Sack" is the shelter that we suggest:

My friends and I each carry an Essential insulating
12 x 12 inch "butt pad" in our daypacks year around and in winter we also carry a larger 24 x 48 inch
Essential insulating pad such as the Cascades Designs Ridge Rest Short (inexpensive
and only 6 oz.) secured to the outside of each person's
winter pack to insulate us from the snow
while sitting for lunch or sheltering while stranded.Our winter day packs
are large enough to carry extra hats and gloves and enough extra insulating clothing
layers including puffy down or pile
jackets (and sometimes down pants) and our light Gore-Tex hooded jacket and side
zip pants to keep us protected from wind and wet.

A plastic space blanket is not a substitute for your winter layers including
puffy synthetic or down insulation and Gore-Tex clothing used with the Emergency
Bivy Sack described below.An inexpensive basic alternative to an expensive space blanket for each member
of a family group as suggested in Backpacker Magazine, by Search and Rescue
Volunteers and some "survivalists", is a heavy gage plastic trash bag.
(A packaged plastic space blanket can be carried in your
Group First Aid Kit to provide a clean area on which to tend an injured companion.)

(This 9 oz. Essential Shelter is about the size of a soft, chubby one quart Nalgene bottle)

The new Thermo-lite Escape Bivvy starts
shipping to stores in January, 2012

"The Escape Bivvy is nothing less than a revolution in
backcountry shelters. The complaint with most ultralight emergency shelters is
the same: condensation builds up inside as you get warm, leaving your clothes
soaking wet. With the Escape Bivvy, condensation is no longer an issue, and you
never again have to choose between staying dry and staying warm. The proprietary
fabric lets moisture escape at the same time that it keeps rain, snow, and wind
on the outside – all while reflecting your body heat back to you. Waterproof
seams plus a drawstring hood closure and side zip mean you can seal out the
elements entirely or use the bivvy like a traditional sleeping bag, and the
high-visibility orange exterior makes it easy for rescuers to spot you even in
areas with high tree cover." Cost about $50.00, weight about 9 oz.

"Adventure Medical Kits was raising money for NOLS scholarships
at Outdoor Retailers Winter Market with a deal for their new SOL Escape Bivvy.
Already turning heads at the show and winning awards, the bivvy will go on sale
later this year."

Carried summer and winter, tucked in a little corner in the
bottom of your day or summit pack, this answer (with an insulating 6 oz. pad) to the 10th Essential System,
"SHELTER", should last a lifetime of adventures.

"The diminutive, weather-resistant E-Bivy sack adds the ideal
amount of protection for wide range of situations without adding much to your
pack. It will block wind, dew, spindrift and even light precipitation, adding
valuable warmth and comfort when used under tarps, on open bivies and for winter
camping. It can also be tossed into a pack lid on any trip, providing essential
protection for an unplanned night in the hills.
Highly Breathable: Increased fabric breathability minimizes internal
condensation.
Versatile: Silnylon top and tough, DuraShield™-coated waterproof bottom protect
from dew, frost, wind and light precipitation while adding warmth to any sleep
system.
Compact: Weighs a mere .25 kg (9 oz.) and packs ultra-small."